Borough of Norristown, PA Traffic Impact Study

Purpose. The traffic impact study will enable Norristown to assess the impact of the proposed development on the transportation system, both highways and public transportation, in Norristown. The purpose of the impact study is to ensure that proposed developments do not adversely affect the transportation network and to identify any traffic problems associated with access between the site and the existing transportation network. The study's purpose is also to delineate solutions to potential problems and to present improvements to be incorporated into the proposed development. The study shall assist in the protection of air quality, conservation of energy and encouragement of public transportation use.

A traffic impact study shall be prepared by a qualified traffic engineer and/or transportation planner licensed in the State of Pennsylvania with previous traffic study experience. Procedures and standards for a traffic impact study are as set forth herein.

Applicability.

A traffic impact study shall be submitted as part of all subdivision, land development and conditional use applications for:

All residential subdivisions or land developments of 20 dwelling units/lots;

All commercial, office, industrial, institutional or other uses generating 40 new vehicle trips entering or exiting the development in any one-hour period; or

In the opinion of the Municipal Engineer, the development is expected to have a significant impact on highway safety or traffic flow, even if the above conditions in Subsection 3.A.1) and 2) are not met.

If the development has multiple stages or phases, the need for the traffic impact study shall be based on the full build-out of the development.

The Municipal Council, at its discretion, may require any other subdivision or land development application to be accompanied by a traffic impact study; provided, however, that the Municipal Council notifies the applicant within 60 days following the Municipal Council's first meeting to consider the proposal. Such a notification shall specify the reason for the requirement, citing the proposal's particular location or existing problems or type of use. The Municipal Council, at its discretion, may waive the requirement for a traffic impact study. If required by the Municipal Council, the developer of a land development shall provide emergency signal preemption for any traffic signals located within or immediately adjacent to the development. An application which requires a traffic impact study shall not be considered complete until the traffic impact study is submitted to Norristown in accordance with the provisions of this section.

Definitions. As used in this section, the following terms shall have the meanings indicated:

ENGINEERING AND TRAFFIC STUDIES – Shall be prepared in accordance with the Pennsylvania Code, Title 67, Chapter 201, Engineering and Traffic Studies.

LEVEL OF SERVICE – As described in the 2000 Highway Capacity Manual, indicates how well traffic moves on a particular highway facility or through a specific intersection. There are six levels of servicing ranging from "A" through "F". Level of Service "A" indicates generally free movement. Level of Service "F" represents maximum capacity of the facility. Level "F" indicates congestion. Level of Service "C" is considered the design level of service, representing a stable traffic flow and a relatively satisfactory travel speed.

MAJOR INTERSECTION – Any intersection where traffic generated by the proposal will have significant impact on the operation of the intersection and/or any other intersection involving an arterial road. Where doubt exists, the traffic engineer shall seek guidance from the Norristown Engineer prior to the submission of the traffic impact study.

PUBLIC TRANSPORTATION – Transportation service for the general public provided by a common carrier of passengers generally on a regular route basis, or a private operator offering service to the public.

QUEUE ANALYSIS – This procedure includes the average queue and maximum queue of vehicles which will be observed in each traffic stream and intersection approach, measured in both feet and vehicles. Various statistical and/or computer models may be applied.

STUDY AREA – This area will extend approximately 1/2 mile along the adjacent roadways in all directions from all access points or the first major intersection along these roadways. Where doubt exists, the traffic engineer shall seek guidance from the Norristown Engineer prior to the submission of the traffic impact study.

TRIP GENERATION RATES – The total count of trips to and from a study site per unit of land use, as measured by parameters such as dwelling units, acres, etc.

VOLUME/CAPACITY ANALYSIS – This procedure compares the volume of a roadway or intersection approach to its capacity (maximum number of vehicles that can pass a given point during a given time period.) The procedures described in the 2000 Highway Capacity Manual (latest edition), Highway Research Board Special Report 209, shall be followed.

WARRANTS FOR TRAFFIC SIGNAL INSTALLATION – This is a series of warrants which detail the minimum traffic or pedestrian volumes or other criteria necessary for the installation of a traffic signal. These warrants are contained in the Manual on Uniform Traffic Control Devices for Streets and Highways, United States Department of Transportation, Federal Highway Administration, 2003, as amended, or the most-recent version, whichever is later.

General requirements and standards. A traffic impact study shall contain the following information:

General site description.

The site description shall include the size, location, proposed land uses, construction staging and completion date of the proposed subdivision or land development. If the development is residential, types of dwelling units shall also be included. A brief description of other major existing and proposed developments within the study area shall be provided. The general site description shall also include probable socioeconomic characteristics of potential site users to the extent that they may affect the transportation needs of the site (i.e., number of senior citizens).

Photographs should be obtained and labeled for all the study intersections and proposed access driveways. It is recommended that two views be taken of each approach for the intersections. Photographs should consider elements such as horizontal/vertical alignment of roadways, trees, buildings or other roadside objects, pavement markings, drainage, signal heads and placement:

Approximately 200 feet from the intersection to provide an overview of the study area and overall study context.

Approximately 50 feet from the intersection.

Transportation facilities description.

The description shall contain a full documentation of the proposed internal and existing external transportation system. This description shall include proposed internal vehicular, bicycle and pedestrian circulation, all proposed ingress and egress locations, all internal roadway widths and rights-of-way, parking conditions, traffic channelization and any traffic signals or other intersection-control devices at all intersections within the site.

The report shall describe the entire external roadway system within the study area and include discussion of existing design deficiencies and potential safety hazards. Major intersections in the study area shall be identified, photographed and sketched. All existing and proposed and public transportation services and facilities within a one-half-mile radius of the site shall also be documented. The applicant shall identify all existing and proposed pedestrian and bike facilities that would be affected by the proposed development. Pedestrian facilities include sidewalks, intersection treatments, and off-road paths or trails. Bicycle facilities include on-street bike lanes, paved shoulders, and off-road paths or trails. The traffic impact study shall include review and discussion of all available accident reports within the study area during the prior three years.

All future highway improvements, including proposed construction and traffic signalization, shall be noted. The four-year Regional Transportation Improvement Program maintained by the Delaware Valley Regional Planning Commission and the PennDOT Twelve-Year Plan shall be used as a source of information when determining if any future roadway improvements are scheduled for the adjacent road network. Any proposed roadway improvements due to proposed surrounding developments shall be recorded.

Existing traffic conditions. Existing traffic conditions shall be measured and documented for all roadways and intersections in the study area. Existing traffic volumes for average daily traffic, peak highway hour(s') traffic, and peak development-generated hour(s') documentation shall be included in the report. Traffic counts are to be performed from 6:00 a.m. to 10:00 a.m. and from 3:00 p.m. to 7:00 p.m. Traffic count data shall not be more than one year old. Traffic counts shall be taken on a Tuesday, Wednesday, or Thursday of a nonholiday week. Traffic counts shall be taken during the school year. Traffic counts shall be collected during average volume conditions, during fair weather, and in consideration of any construction activities or special events which may be taking place in the area. Additional counts (conducted on a Saturday for a commercial development or residential development in close proximity to the commercial district or tourist attractions) may also be required in some cases. The Norristown Engineer shall make such determinations. Traffic counts shall be submitted in electronic format to Norristown. Roadway characteristics shall be described and illustrated. Features to be addressed shall include lane configurations, geometry, signal timing, traffic control devices, posted speed limits, and sight distance limitations. Existing levels of service shall be calculated for all intersections and turning movements within the study area. This analysis will determine the adequacy of the existing roadway system to adequately serve the existing traffic demand. Roadways, intersections, or individual movements experiencing levels of service below C, and/or volume/capacity ratios greater than or equal to 1.0, shall be noted as deficient. A volume/capacity analysis based upon existing volumes shall be performed during the peak highway hour(s) and the peak development-generated hour(s) for all roadways and major intersections in the study area. Levels of service shall be determined for each location using the current edition of the Highway Capacity Manual methodology. All analysis must utilize Highway Capacity Software, version 4.1e, or latest.

Transportation impact of the development. Estimation of vehicular trips to result from the proposal shall be completed for the average daily peak highway hour(s) and peak development-generated hour(s). Vehicular trip generation rates to be used for this calculation shall be obtained from the manual Trip Generation, Eighth Edition, Institute of Transportation Engineers, 2008 (as amended). These development-generated traffic volumes shall be provided for the inbound and outbound traffic movements as estimated, and the reference source(s') methodology followed shall be documented. All turning movements shall be calculated. These generated volumes shall be distributed to the study area and assigned to the existing roadways and intersections throughout the study area. Documentation of all assumptions used in the distribution and assignment phase shall be provided. Traffic volumes shall be assigned to individual access points. If school crossings are to be used, pedestrian volumes shall be assigned to each crossing. Any characteristics of the site that will cause particular trip generation problems shall be noted.

Analysis of transportation impact.

The total future traffic demand shall be calculated. This demand shall consist of the combination of the existing traffic expanded to the completion year (using a background growth rate for the area from PennDOT, Pennsylvania Traffic Data, latest edition), the development-generated traffic, and the traffic generated by other proposed developments in the study area. A separate trip distribution figure shall be provided. A second volume capacity analysis shall be conducted using the future conditions' volumes without development. This analysis shall be performed during the peak highway hour(s) and peak development-generated hour(s) for all roadways and major intersections in the study area. Level of service calculations shall be completed for all major intersections. A third volume capacity analysis shall be conducted using the total future demand and the future roadway capacity.

If staging of the proposed development is anticipated, calculations for each stage of completion shall be made. This analysis shall be performed during the peak highway hour(s) and peak development-generated hour(s) for all roadways and major intersections in the study area. Level of service calculations shall be completed for all major intersections. It is usually at these locations that capacity is most restricted. All access points and pedestrian crossings shall be examined as to the feasibility of installing traffic signals. This evaluation shall compare the projected traffic and pedestrian volumes to the warrants for traffic signal installation.

Sight distance analysis. Sight distance measurements shall be performed at any proposed driveway and/or existing driveway to determine sufficient sight distance to the left and right of the driveway. Sight distances shall be compared to the desirable sight distance standards as specified in Title 67 of Pa. Code, Chapter 441, Access to and Occupancy of Highways by Driveways and Local Roads, April 2006. Sight distance shall also be compared to PennDOT's safe stopping sight distance (SSSD) requirements as specified in A Policy on Geometric Design of Highways and Streets (5th Edition), of the American Association of State Highway and Transportation Officials (ASSHTO), Chapter III, Elements of Design, 2004.

Auxiliary lane analysis. An auxiliary lane analysis shall be completed utilizing Highway Research Record (HRR) 211 (1967). HRR 211 provides graphs based upon the speed of the roadway and the percentage of left turns. Utilizing the future build with development traffic volumes, points shall be plotted on the graphs. Based on the plotted points, it should determined that the study area intersections associated with the proposed developments do or do not satisfy the left-turn-lane warrant. Right-turn-lane analysis should be based upon the Access Management, Location and Design Participant Notebook, Publication Number FHWA-HI-92-033, United States Department of Transportation, Federal Highway Administration NHI Course Number 15255, February 1992. Deceleration lanes should be provided for all high-volume driveways. For low- and medium-volume driveways, the designer should refer to the AASHTO at-grade intersections deceleration lane warrants.

Conclusions and recommended improvements.

Levels of service for all roadways and intersections shall be listed. All individual turning movement of roadways and/or intersections showing a level of service below "C" shall be considered deficient, and specific recommendations for the elimination of these problems shall be listed. This listing of recommended improvements shall include, but not be limited to, the following elements: internal circulation design, site access location and design, external roadway and intersection design/safety improvements, traffic signal installation and operation, including signal timing, and transit design improvements. All physical roadway improvements shall be shown in sketches.

Existing and/or future public transportation service shall also be addressed. A listing of all actions to be undertaken to increase present public transportation usage and improve service, if applicable, shall be included.

The listing of recommended improvements for both roadways and transit shall include, for each improvement, the party responsible for the improvement, the cost and funding of the improvement, and the completion date for the improvement.

The study shall outline mitigation measures and demonstrate any changes to the level of service achieved by these measures. Any alternatives or suggested phasing of improvements shall be described. The mitigation measures may include recommendations such as roadway widening, turning lanes, deceleration lanes/tapers, changes to signalization, use of access management techniques, or a reduction in the proposed intensity of the use. The responsibility and timing of all recommended roadway improvements shall be described within the traffic impact study.

Time of submission. The traffic impact study shall be submitted to the Planning Commission with the preliminary plan submission. Revisions to preliminary plans may constitute the need for resubmission of the traffic impact study or the revised conditions. See Figure 4.24.[1]

[1]

Editor's Note: Figure 4.24 is included at the end of this chapter.

Implementation. The Municipal Council shall review the traffic impact study to analyze its adequacy in solving any traffic problems that will occur due to the land development or subdivision. The Municipal Council may determine that certain improvements on and/or adjacent to the site and within the study area are necessary requirements for land development or subdivision plan approval and may attach these as conditions to the approval. If the governing body determines that such additional improvements are necessary, the developer shall have the opportunity to submit alternative improvement designs to obtain plan approval.

Emergency response organizations. Norristown shall submit the traffic impact study with the land development plans proposing the construction of nonresidential buildings or multifamily residential dwellings to the Fire Department, Police Department and any other emergency response organization having jurisdiction within the area of the proposed development for review and comment.